38 M.R.S. §591: Prohibitions

No person may discharge air contaminants into ambient air within a region in such manner as to violate ambient air quality standards established under this chapter or emission standards established pursuant to section 585, 585‑B or 585‑K.

When the board, pursuant to section 590, has by rule provided that no person may operate or maintain within a region any air contamination source or emit any air contaminants without an emission license from the department, the operation or maintenance without that license is prohibited.